1. Field of the Invention
The present invention relates to a treatment device in accordance with the preamble of claim 1, which has a tool driven by a drive unit and means for delivery of a cooling medium to a treatment site worked by the tool. In particular the present invention relates to a dental treatment instrument having a drill which can be set in rotation by a drive.
2. Description of the Related Art
In the treatment of caries or other dental treatments, working steps in which a part of the tooth substance must be removed are often unavoidable. The classical treatment tool for carrying out such work is a dental drill, which is arranged in the head region of a treatment instrument and is set into rotation by means of a drive unit. Depending on the configuration of the surface of the drill, and of the drive, there can then be set a certain material removal power. Thereby, modern dental hand instruments offer in particular also the possibility of varying the power.
In all dental treatments it is to be taken into consideration that the human tooth is a living organism which is connected with the remaining organism via the so-called tooth pulp. In the treatment of a tooth, in particular in the removal of tooth material by means of a drill, heat now arises at or in the tooth, scientific investigations having shown that at temperatures above 41° C. the tooth pulp dies off and correspondingly damage to the tooth arises.
In order correspondingly to avoid that during the treatment temperatures of more than 41° C. arise at the tooth pulp, it has long been known to deliver to the treatment site worked with the drill a cooling medium, for example, water, air or a water-air mixture. With regard to the desired cooling, cooling via a water-air mixture in the form of a spray has proved to be particularly effective, whereby as a general rule it is accepted that a cooling quantity of 50 ml per minute brings about an adequate cooling. This knowledge is again based on scientific investigations. The water-air mixture or spray is then directed at the treatment site by means of nozzles in the head region of the dental instrument.
Disadvantageous with the known spray cooling, is, however, that through this the view of the area being prepared is made worse by an aerosol mist consisting of water, air and removed particles of the tooth. This aerosol cloud, during the treatment, emerges from the mouth of the patient and contaminates the surroundings of the dental treatment station. Since the water-air mixture is further breathed in by the person carrying out the treatment, beyond this there is also an increased risk of infection.
The material removal power put to use and needed by the dentist during the treatment is subject to large variations. In order to ensure that even at the maximum removal power still usual in practice, an adequate cooling is effected, the spray quantity must correspondingly be so set that this is still adequate also for these high power ranges. This leads to the usually employed cooling quantity already mentioned above, of 50 ml water per minute.